In the typical well that is treated by conventional sand control processes, the production liner is first perforated and then a sand control completion system is run in the hole. The sand control system comprises of a fluid barrier device such as a ball valve or flapper valve that closes when the treating string is removed from the wellbore after the treatment is performed. The well barrier device provides isolation for the wellbore from the formation, and allows for other operations to be performed in the wellbore prior to producing. Wellbore operations prior to production are performed above the fluid barrier device. For example, production tubing can be run in the hole and, once properly sealed, the fluid barrier device is opened mechanically and the well is produced.
However, the production liner may comprise of a series of casing valves. The casing valves have a sleeve for isolating a port that allows fluids to flow between the wellbore and the formation. Typically, the casing valves are cemented in the open hole and the sleeves are moved away from the port, thus providing access to the formation. The casing valves are opened so that treating of the formation can be performed. The treating may comprise pumping slurry to fracture the formation. The sleeves are positioned by mechanical methods, such as collets or key type shifting tools attached to a work string. The work string is moved up and down to position the sleeve. The casing valves can be left open after the treatment. To provide wellbore isolation from the formation, a fluid barrier device can be placed above the top-most casing valve of the production liner. When the treating string is removed, the fluid barrier device is closed, and the wellbore above the production liner is isolated from the formation. The wellbore in the production liner is exposed to the formation, however, and access below the fluid barrier is prevented.